采用抛物线形竖曲线时,每20m竖曲线长度的变坡率,凹型应不大于()。
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What specific jobs do securities outside dressing rooms do？
A. In addition to ensuring the life style of the performers, they should prevent any person from entry.
B. In addition to ensuring the life safety of the actors, they should stop any reporters from entering
C. In addition to ensuring the life safety of the performers, they should prevent any fans from entering
D. In addition to ensuring the life safety of the performers, they should prevent any unauthorized person from entering
导曲线根据需要设置6mm超高,并在导曲线范围内按不大于()顺坡。
其它站线道岔轨道静态经常保养直线轨向容许偏差管理值为()。
How long should we keep the video tapes of surveillance cameras？
A. You should keep the video tapes for at least five months.
B. The video tapes should be kept for at least three months.
C. You should keep the video tapes for at least one month
D. You should keep the video tapes for at least two months.
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